1. Field of the Invention
The present invention relates to magnetic recording media formed by thin film deposition methods, and specially to magnetic recording media excellent in corrosion resistance.
2. Description of the Prior Art
In recent years, the research and development of magnetic recording media have become active on the production thereof by thin film deposition methods such as vacuum deposition, sputtering, and plating methods. These methods fullfil the requirements of high density recording to a great extent in that (1) the resulting recording media exhibit high residual magnetic flux density, (2) magnetic recording media have strong coercive force can be formed, and (3) thin magnetic recording layers can be formed. Alloys constituted principally of Co and Ni have hitherto been used as magnetic materials for those recording media. In particular, a Co-20 wt. % Ni alloy has been studied extensively. Reasons for this, generally considered, are that; this alloy has relatively high corrosion resistance; such alloys containing 70 wt. % or more of Co have h.c.p. structure (hexagonal close-packed structure); and the magnetic field anisotropy thereof can be controlled with ease to excellent in-plane anisotropy.
However, this kind of alloy is very expensive because of the Co content as high as 70% or more, usually about 80%. An additional problem is that the price of Co much varies with the international situation. The corrosion resistance of these alloys also is unsatisfactory under harsh environmental condition.